Re: IPv6 default routes / NM vs. kernel autoconfig vs DHCP6

[Stuart D Gathman <stuart gathman org>]

On 08/03/2012 05:33 PM, Dan Williams expounded in part:
> That's correct, but at the time that bug was filed I did not know enough
> about IPv6 configuration to suggest the correct course of action.  I now
> know much more and realize that adding it back was a mistake.  We should
> really deprecate that option and just alias it to "automatic".
>
> DHCPv6-only without RAs is fundamentally broken.  Any valid
> configuration needs RAs, if only for the default route.
One situation that ought to work IMHO (although ~1/2 of IPv6 experts 
disagree) is that DHCP6 should work in concert with routes that are not 
/64.  For instance, RA provides a 2001:db8:1:2:3::1/80 default route, 
sets the M bit, and DHCP6 provides the address
2001:db8:1:2:3::1000.  NM should be able to set the default route *and* 
apply the /80 prefix length to the DHCP6 address.  This could get 
non-trivial when there are multiple routes provided by RA.  NM must then 
find the route that matches the DHCP6 address to determine the correct 
prefix.

Note: the experts that disagree feel that all LANs should be /64 always 
forever, and prefixes should only be used in routers.  I find it quite 
handy to be able to subnet the /64 provided by the ISP, and while I 
agree that ISPs should always forever allocate a minimum of /64 to end 
users, nevertheless endusers should be able to subnet that and still 
have workstations and devices work without manual configuration.